The invention relates to the use of carboxylic acid fluorides as pesticides. It is known in the art to use sulfuryl fluoride as a pesticide; see U.S. Pat. No. 2,875,127, for example. Pests or fungi can be controlled, for instance, in installed or uninstalled building timber, even in freshly cut timber. Buildings attacked by pests, such as beetles or termites, as well as storage areas can be disinfested. Also known is the disinfestation of museums, churches, or mills. It is also known to use sulfuryl fluoride in combination with carbon dioxide, inert gases, or other pesticides.
In accordance with the invention it has been found that carboxylic acid fluorides can be used as pesticides. The term “carboxylic acid fluorides” preferably encompasses carboxylic acid fluorides containing a total of 2 to 7 carbon atoms. Preferred are aliphatic carboxylic acid fluorides. Compounds with a saturated alkyl group are especially preferred. Also usable are carboxylic acid fluorides that have one or more carbon-carbon double or triple bonds. The alkyl, alkenyl or alkynyl group can also be substituted, e.g., by 1 or more halogen atoms, e.g., 1 or more fluorine atoms. Particularly useful are carboxylic acid fluorides with a total of 2 to 4 carbon atoms, especially those with saturated alkyl groups. They can be substituted by 1 or more halogen atoms, preferably chlorine and/or fluorine atoms. Particularly preferred carboxylic acid fluorides are fluorides corresponding to the formula RC(O)F, where R represents methyl, ethyl, difluoromethyl, trifluoromethyl and difluorochloromethyl. The boiling point of preferred carboxylic acid fluorides is preferably less than 45° C., especially less than 35° C.
If desired, the carboxylic acid fluoride can be used in combination with other pesticides (fumigants). Carboxylic acid fluoride can, for instance, be used together with inert gases (nitrogen, noble gases) and/or carbon dioxide. The inert gases and CO2 can serve as auxiliary gases, for example as carrier gases, e.g., in compounds with a higher boiling point. Other fumigants can of course also serve as carrier gases. However, inert gases and CO2 also have pesticidal properties. The carboxylic acid fluoride and the other fumigant(s) and/or CO2 can be used premixed or separately, simultaneously or successively, or overlapping in time. Preferred pesticides used in addition also have a boiling point of less than 100° C. under normal conditions, preferably less than 45° C., particularly less than 35° C. Alternatively, an atomizing agent can be used. Carbon dioxide has the advantage that the carboxylic acid fluoride concentration can be reduced, since carbon dioxide increases the toxicity of the carboxylic acid fluorides (increased respiration rate of the pests).
It is, of course, also possible to take measures that are typically used in fumigation processes and are known per se. For instance, moisture can be reduced during fumigation, e.g., by introducing drying agents (e.g., SiO2) or by guiding the treatment gas atmosphere continuously or discontinuously across a drying agent. Fumigation may be carried out in several steps. For initial fumigation, the conditions, particularly with respect to the fumigant concentration, are selected so that the larvae and the adults are destroyed. The second and possibly a third or additional fumigation steps are carried out if eggs that were not previously destroyed develop into larvae or adults. It is known that the fumigant concentration to combat larvae or adults can typically be lower than the concentration necessary to destroy eggs. If the concentration is selected such that only the larvae or the adults are destroyed but the process is repeated several times whenever new larvae or adults have developed, the use of fumigant can be reduced.
As an alternative, fumigation may also be carried out using fumigants that are known ovicides, e.g., in combination with hydrocyanic acid, formic acid esters, alkylisothiocyanates or PH3. If desired, the fumigation process may also be carried out in combination with atomizing agents, such as pyrethroids, as described in published German patent application no. DE-OS 197 47 648. As disclosed in Austrian Patent 154,481, it is also possible to arrange a balloon in the room to be fumigated so as to reduce the room volume and thus to save fumigant.
In the method according to the invention, one or more carboxylic acid fluorides can be used as the only pesticide. It is also possible, however, to use carboxylic acid fluoride(s) in combination with other pesticides. For instance, carboxylic acid fluorides can be used together with one or more pesticides selected from the group consisting of sulfuryl fluoride, sulfuryl chlorofluoride, nitrogen, noble gases, carbon dioxide, carbonyl sulfide, PH3, alkyl phosphines (mono-, di- and trialkyl phosphines), SF6, inorganic and organic compounds with the CN group, organic esters, organic nitro compounds, halogenated hydrocarbons, alkynols, thiocyanate esters, isothiocyanate esters, chloropicrin, ethylene oxide, sulfonyl fluorides, and the aforementioned atomizing agents. The esters used are preferably alkyl esters, for instance, alkyl esters of formic acid, acetic acid, etc. Chloropicrin can be used as a warning agent.
The usefulness of carbonyl sulfide as a fumigant is disclosed in U.S. Pat. No. 6,203,824 (=WO 93/13659). Suitable formic acid esters are disclosed, for instance, in published German patent application no. DE-OS 197 47 640. Suitable acetic acid esters are described in published German patent application no. DE-OS 197 58 318. Suitable alkynols or thiocyanate esters are described in published German patent application no. DE-OS 198 01 332. Other carbonic acid esters are described also in published German patent application no. DE-OS 198 13 894. Useful nitro compounds are set forth in published German patent application no. DE-OS 198 04 508. Suitable sulfonyl fluorides are disclosed in German patent DE 196 33 595. Hydrocyanic acid and CF3CN may also be used as CO fumigants.
The pest control method according to the invention may be used for any purpose. For instance, rooms where the pests reside can be fumigated, e.g., storage areas, museums, churches, mills, cargo holds of ships, railroad cars, and silos. Individual goods to be fumigated can be placed into mobile tents. Mobile chambers, containers, even buildings, e.g., residential buildings, can be fumigated. It is of course useful to seal the corresponding rooms or containers, so that no fumigant can reach the environment. The containers or buildings can also be wrapped in foil in a known manner to prevent treatment gas from escaping into the atmosphere. A seal to prevent gas exchange, as described in the Internet under http://www.morse-associates.com/pressure.html, in the chapter entitled “Relative Pressure in Work Area,” can also be ensured by adhesive tape, strippable coatings, or caulking. Both installed or uninstalled building timber can be treated. For instance, freshly cut or sawed timber can be placed into a tent, a fumigation chamber, or a foil envelope for fumigation. This can prevent the spreading of pests in export/import (quarantine fumigation).
Preferably, the method according to the invention is used for controlling the known storage pests and material pests (particularly wood pests), e.g., the tobacco beetle, the grain weevil, moths, flour mites, rice weevils, deathwatch beetles, woodworms, house longhorn beetle, or carpet beetles. The method can also be used to control termites.
The method according to the invention may also be used for soil fumigation. In this case, for instance nematodes and other vermin are destroyed.
Measures that are typically used in fumigation may be taken, e.g., working at an elevated temperature. It is advantageous if the temperature in pest control is at least 10° C., preferably between 15° and 35° C. The work is preferably done at a temperature that is at maximum 3° C. below the boiling point of the compound. Particularly preferred is fumigation at or above the boiling point. This is why carboxylic acid fluorides with their relatively low boiling point are particularly suitable for temperature-sensitive materials.
To achieve a high mortality rate of the storage, soil and wood pests as well as rodents, harmful insects or fungi to be controlled, the concentration preferably ranges from 0.1 g/m3 to 200 g/m3, and the duration is adjusted accordingly. The higher the concentration, the shorter is the contact time required.
The treatment gas can be delivered via water or alkaline solutions or alkali and is subsequently decomposed into harmless compounds. The gas may also be recovered through sorption, e.g., on a molecular sieve or activated carbon. Thermal decomposition or catalytic decomposition (incineration, pyrolysis, high-temperature hydrolysis) is also possible.
The invention also relates to mixtures of carboxylic acid fluorides and at least one other known pesticide. The preferred additional pesticides are the aforementioned agents. Mixtures of carboxylic acid fluorides and CO2, in the form of a gas, liquid or solid, are particularly preferred. These mixtures may also contain additional pesticides.
The invention broadens the spectrum of useful fumigants, for which there is currently a desperate need, since MeBr has meanwhile been found to damage the ozone. Carboxylic acid fluorides act very quickly, which is of course advantageous in practice. After hydrolysis, acetyl fluoride forms acetic acid, which is found in nature.
Carboxylic acid fluorides can be produced, for example, from carboxylic acid chlorides and HF adducts of amines as described in co-pending U.S. patent application Ser. No. 09/856,909 (=WO 00/32549), the disclosure of which is incorporated herein by reference.
The following examples are intended to illustrate the invention in further detail, without limiting its scope.